1. Field of the Invention
The present invention generally relates to a method for forming a semiconductor device, and more particularly to a method for reducing hole defects in the polysilicon layer.
2. Description of the Prior Art
Flash memory is the most potential memory in the semiconductor industry. Flash memory has been broadly applied to repeatedly access data and to remain assessable during power break down, such as the film of digital camera or the basic input-output system of a motherboard. Because flash memory has the advantages of electrically erasable and programmable mechanisms, it can simultaneously proceed the erase and the program mechanisms to all flash memory cells in the whole memory array. Accordingly, how to advance the performance and reduce the cost of the flash memory became an important subject.
Anti-reflective coatings have been used in the fabrication of small dimension integrated circuits (ICs) to provide better control over the photolithographic process. In particular, organic BARCs (bottom anti-reflective coatings) have been used during the contact hole masking step to reduce the reflections from the underlying topography substrate and thereby provide better control over the width of the photoresist mask openings which are used to form contact holes of a desired width.
Referring to FIG. 1A, firstly, a semiconductor substrate 100 is provided, and a polysilicon layer 102 is formed over a semiconductor substrate 100. Then, a silicon oxide layer 104 is formed over the polysilicon layer 102. A bottom anti-reflective coating (BARC) layer 106 is formed on the silicon oxide layer 104 by using spin-coating method, wherein the bottom anti-reflective coating (BARC) layer 106 has a micro bubbles 107 therein. A photoresist layer 108 is formed on the bottom anti-reflective coating (BARC) layer 106 by using spin-coting method. The photoresist layer 108 has an opening by using conventional lithographic technology.
Referring to FIG. 1B, the bottom anti-reflective coating (BARC) layer 106, the silicon oxide layer 104, and the polysilicon layer 102 are etched by using the photoresist layer 108 as a mask. Because the bottom anti-reflective coating (BARC) layer 106 has micro bubbles 107 therein, the active area interface between the substrate 100 and the polysilicon layer 102 has hole defects. Then, the photoresist layer 108 is removed.
For the forgoing reasons, a necessary method for reducing hole defects in the polysilicon layer is required. The solvent and bake treatment can reduce hole defects in the polysilicon layer.
In accordance with the present invention, a method for reducing hole defects in the polysilicon layer that substantially can reduce hole defects in the polysilicon layer in conventional process.
One object of the present invention is to provide a method for reducing hole defects in the polysilicon layer to improve the hole defects issue.
In order to achieve the above object, the present invention provides a method for reducing hole defects in the polysilicon layer. The method at least includes the following steps. First of all, a semiconductor substrate is provided, a polysilicon layer is formed over the semiconductor substrate. Then, no hole defects bottom anti-reflective coating process is performed, wherein the no hole defects bottom anti-reflective coating process is selected from the group consisting of dehydration baking, hydrophobic solvent treatment, and steady baking. Finally, a bottom anti-reflective coating is formed over the polysilicon layer.